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Fukushima: 2.5 times more radioactive xenon than Chernobyl

Study: Release immediately after earthquake – before tsunami

An international team of researchers from Norway, Austria, Spain and the United States concluded in a study, published on October 21, that the amount of the noble gas xenon 133 released during the Fukushima disaster was a factor 2.5 times higher than released in Chernobyl. According to their report, there is “strong evidence“ that the start of the release was on March 11 at about 3 pm (Japanese time) and therefore before the tsunami hit the coast. This leads the scientists to believe that the earthquake at 2.46 pm may have led to “structural damage” of the reactor.

„The results of this study are further evidence refuting claims that the earthquake was not the reason for the disaster, but only in combination with the tsunami, made by the nuclear industry, the Japanese government and the German Reactor Safety Commission,“ said Henrik Paulitz, nuclear expert of the international physicians’ organisation IPPNW. „The attempt by the nuclear lobby to play down the massive risk for reactors posed by earthquakes has failed once and for all due to the publication of this new study. It is quite astounding to see how the Reactor Safety Commission and other German government bodies insist on clinging to this barely credible tsunami theory – probably to try to avoid reactors situated in earthquake regions, such as Philippsburg-2 and Neckarwestheim-2, from coming under political attack.“

The Norwegian Institute for Air Research led the study on Fukushima, and the Austrian Central Institute for Meteorology and Geodynamics (ZAMG) in Vienna and others took part. The authors calculated that a total of 16700 PBq xenon 133 was released between March 11 and 15 - „the largest radioactive noble gas release in history not related to nuclear bomb testing“. The scientists collated approximately 1000 concentration and deposition measurements of radiation in Japan, the United States and Europe in order to produce this study, regarded as the most comprehensive to date.

The release of caesium 137 – known to be particularly dangerous for human health – in the months of March and April were approx. 36 PBq, according to the authors. Although only nearly 2% of the total caesium 137 inventory contained in the Fukushima Units 1 to 3 and the spent fuel pool at unit 4, the amount released in the period of time studied adds up already to 42% of the estimated release from the Chernobyl reactor. Due to weather conditions (prevailing west wind, low precipitation) approx. 20% of the released caesium 137 fell on the Japanese mainland, the remaining 80% over the Pacific Ocean.

The massive release of caesium that occurred early on March 12 during the first hydrogen explosion in unit 1 has been underestimated until now, according to the authors. Exactly during and following the highest rates of caesium emissions on March 14 and 15, large areas in the East of the Japanese mainland, Honshu Island, were affected. Unexpectedly high levels of caesium 137 emissions also occurred between March 16 and 19 which were apparently reduced by the initiation of cooling of the spent fuel pool of unit 4.

Fortunately, the metropolitan area of Tokyo with its 36 million inhabitants escaped the worst because there was no rain at the time when the densest part of the radioactive plume passed over the capital on March 15. On the other hand, radioactive fallout affected large areas of the Japanese mainland between March 20 and 22 from the region north of the Fukushima nuclear plant to Osaka in the south. This was followed by heavy rain that nearly completely cleansed the atmosphere of caesium 137. Large areas of Japan, including Tokyo, therefore received a considerable amount of exposure to caesium.

Former Prime Minister Naoto Kan recently made clear how dramatic this period of time really was in revealing that his government had considered evacuating Tokyo. This would have meant that Tokyo would have become an exclusion zone. In that instance, Kan said that he doubted that Japan could have continued to function as a state.